SECT. 1] 



RADIOISOTOPES AND LARGE-SCALE OCEANIC MIXING 



Table IV 



103 



Comparison of Deep-Sea Residence Times, Suess Effect Estimates, and Surface- 

 to-Depth Radium Concentration Ratios for the Various Models 



a Mean time dissolved solids remain in the deep sea before returning to mixed layer. 

 b Incompatible with 14 C distribution. 



Whereas mixing between the surface and intermediate reservoir and between 

 the polar and deep reservoir is relatively rapid, mixing between the combined 

 surface plus intermediate reservoir and the combined polar plus deep reservoir 

 is quite slow. The rate is controlled by the requirement that the 226 Ra con- 

 centration in the upper waters be one-half that in the deep water (i.e. td.s. for 

 the combined surface plus intermediate reservoir equals 1600 years). In this case 



